The present invention generally relates to RF modulators, and more particularly to a 4 phase PSK modulator constructed using micro-strip printed circuit techniques and capable of working at relatively high power so that the RF carrier may be directly modulated.
Previous methods of 4 phase PSK modulation use various IF modulation techniques to produce a 4 phase PSK modulated carrier at some intermediate frequency (often on the order of 70 MHz) which is then translated by an up converter to the desired radio frequency. These methods require considerable circuitry at IF and an up converter to translate the 4 phase PSK signal to the desired radio frequency. The up converter is a low powered device that requires a driver stage, such as a travelling wave tube amplifier, before the high power output amplifier.